Cam



July 24, 1962 C. O GLASGQW 3,045,506

CANI

Filed D80. 14, 1960 2 Sheets-Sheet l Si Y / .d El

A lIlllllHA/h INVENTOR. CLARENCE O. GLASGOW Nm ZZ/m .ATTDBNEY July 24, 1962 c. o. GLASGOW 3,045,505

' CAM Filed Dec. 14, 1960 2 sheets-sheet 2 5 INVENTOR.

CLAQENCE o. GLASGOW ATTORNEY ...if Jo- United States Patent O M' 3,045,506 CAM Clarence 0. Glasgow, Tulsa, Okla., assignor to National Tank Company, Tulsa, Okla., a corporation of Nevada Filed Dec. 14, 1960, Ser. No. 75,714 2 Claims. (Cl. 74"-568) The present invention relates to adjustable cams. More specifically, the invention relates to cam structures which provide a rotating surface under a follower with which the follower is shifted between two positions at predetermined points in the rotation of the surface.

It is conventional to cut a predetermined cam prole and rotate the cam profile beneath a follower. A series of cams can be turned together to actuate a series of individual followers to actuate a control system and cause the system to respond to a predetermined pattern to the mechanism attached to the followers.

Cams can be changed and reshaped to modify the control actions generated by their profiles. Attachments have been placed on cams tomodify their profiles. However, a cam structure is not available which does not involve the expedient of recutting the profile of a cam, or adding structures to the cam profile, to modify the actuating surface.

A primary object of the present invention is to develop a cam surface of predetermined profile for actuating a follower by manual repositioning of related components of a cam structure.

Another object is to develop the surface of a flexible element as the actuating surface of a cam for a predetermined angle of rotation of the cam structure.

The present invention contemplates rotating two portions of a cam structure with respect to each other to position a third element of the cam structure into a surface of predetermined length for actuating a follower.

The invention further contemplates a flexible element being drawn from a central recess of a cam structure onto `a peripheral track of the cam structure for a predetermined length of the track and forming an ,actuating surface for a cam follower.

Other objects and advantages and features of this invention will become .more apparent to one skilled in the art upon consideration of the written specification, appended claims and attached drawings wherein;

FIG. l is a perspective illustration of a complete cam structure in which the present invention is embodied;

FlG. 2 is an elevation of the cam structure with one of its plates removed to show the internal arrangement of the cam;

FG. 3 is a cross-sectional end view of the cam taken through its center to illustrate the internal arrangement of the completely assembled cam structure; and

FIG. 4 is a portion of FIG. 3 in the direction of 4 4.

rthe perspective illustration of FIG. 1 represents a motor 1t) rotating a lshaft |11 clockwise at a constant speed. The present invention is embodied in cam 12 which is mounted on shaft 11.

Cam 12 actuates some form of mechanism by positioning a follower-roller 13. More specifically, followerroller 13 is mounted on a pivoted arm 14. As the profile of cam 12 moves under follower-roller 13, arm 14 is pivoted about fulcrum point 15. The cam surface actuates the follower-roller 13 to positions which are `different distances from the center of rotation of shaft FIG. 1 shows arm 14 pivoted about fulcrum point 15 Iand urged against the cam surface by spring 16. When moved upward, .against the `force of spring 16, arm 14 will move valve stem 17 to the alternate of its two positions.

3,645,566 Patented July 24, 19762 ICC Valve stem 17 is a part of the valve mechanism Within body 18. The complete valve structure within body 18 may take the form of the valve manufactured by Barworth, Inc., Springfield, New Jersey, under Patent 2,860,660. This snap-acting valve may receive fluid pressure through pipe 19 and direct such fluid pressure to either pipe 20` or pipe 21, depending on which of its two positions follower-roller 13 is given by the working profile of cam structure 112.

It is to beA understood that the valve structure of body 18 is merely representative of the varied forms of pneumatic, mechanical or electric structures which can be actuated by the pivoting of arm 14 about fulcrum point 15. Representative of such units, the fluid pressure valve of FIG. 1 is expected to be incorporated in a complete control system to carry out a program of control actions.

Cam structure 12 rotates at a fixed speed with shaft 11. The follower-roller actuating surface of cam 12 is predetermined in form by manual manipulation of plate relative to plate 26. Back plate 25 is formed with an integral shaft 27 which is, itself, journaled over motor shaft 11. Front plate 26 is, in turn, journaled over shaft 27 and resiliently urged against back plate 25 with a spring 28.

'Spring 2S isv fixed, by one end, to shaft 27` from a series of set screws 29. Set screws 29 extend radially through shaft 27 and engage motor shaft 11. This arrangement provides a fixed relationship between back plate 25 and shaft 11 and provides the spring loading of front plate 26, which urges it toward back plate 25.

Resiliently urged toward back plate 25, front plate 26 is rotatable on shaft 27. A number of recesses 30 are provided in the edge of front plate 26 to provide a hand-grip and facilitate manual rotation of front plate 26 relative to back plate 25.

A track is provided between back plate 25- and front plate 26 upon which a flexible element is drawn from an internal recess of cam structure 112 for a predetermined length of the track. The flexible element drawn out upon the track forms a raised actuating surface for the follower-roller 13. FIG. l shows the flexible element 31 in position upon the track in FIG- 1. This relation may be analyzed to further advantage in FIGS. 2 and 3.

Referring to FIG. 2, back plate 25 is shown ,in elevation with flexible element 31 extending from the central recess of cam structure 12 formed between shaft 27 and the peripheral track structure provided for the flexible element a uniform distance from the center of plate rotation. The track structure is made up of a base track element in the form of a ridge 32 extending from back plate 25 normal the plane of the rotating plate 25 and a uniform distance from the center of rotation.

An aperture is provided in the ridge 32 at 33, the aperture 33 being sized to permit withdrawal of flexible element 31 from its recess about the center of rotation of the plate. The edges of aperture 33 are suitably shaped to allow the flexible element to be moved into, and out of, the aperture, depending on whether the element is pushed, or pulled, from its external end.

The external end of flexible element 31 is pushed, or pulled, through attachment to front plate 26. More specifically, a strap 34 is clamped to the end of flexible element 31 and pin 35 extended from front plate 26 through strap '34. Manual rotation of front plate 26 will then cause pin 35 to pull the strap 34, and flexible element 31, from aperture 33, or pin 35 will bear against the end of flexible element 31 and Iforce the element back through aperture 33 and down into the internal recess of the cam beneath ridge 32. It is also feasible to simply extend the pin 35 through the material of the element 31 and not the strap 34.

FIG. 3 is established to show track lip 36 on back plate 25 and track lip '37 on front plate 26. These lips extend over the base track ridge 32 to capture the exible element 31 upon -base track ridge 32. The Afollower-roller rides between these lips to engage either the base track ridge 32 or element 31 as this working cam profile is rotated.

FIG. l4 illustrates a speciic arrangement for set screws 29 as they extend through shaft 27 of back plate 2S. Specically, three set screws Iare illustrated, although a lesser, or greater, number may function to fix back plate 25 to motor shaft 11 and anchor one end of spring 28.

The most prominent feature of the cam is the flexible element 31. A material for this element is desired which will give a low degree of friction with the track structure as the element is withdrawn from, and inserted into, aperture 33. There are various types of rubber which are availableI and a number of these are suitable for this service. Also, the friction may be reduced by laminating plastic sheets over the faces of a lilexible rubber element without substantial reduction of its flexibility. Also, leather, or one of the plastics, may be satisfactory to function as required.

Considering other material requirements, the body of plates 25 and 26 may be metal, or one of the plasticrubber combinations. It is anticipated that moulded material will reduce the machine time which would be required for metal. However, Ia die casting might be quite satisfactory for the simple form required to embody the invention.

From the foregoing it will be seen that this invention is one Well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention Without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed 1. A cam including,

afrst plate, K

a base track ridge extending normal the plane of the rst plate and a uniform distance from the plate center,

a first lip extending normal the plane of the rst plate from the periphery of the rst plate,

a second plate arranged manually rotatable about the center of the first plate but to turn with the first plate when the combination normally functions as a cam,

a second lip extending normal the plane of the second plate from the periphery of the second plate,

a spring arranged to urge the plates together as the plates turn together,

and a flexible element attached by one end to the second plate so as to be drawn from beneath the base track ridge through an aperture in the ridge and out upon the base track ridge by the manual rotation of the second platewhere it is captured by the first and second lips in lforming the cam prole for actuating a follower to alternate positions.

2. A cam including;

a tirst circular plate having,

an integral shaft extending normal the plane of the plate and from the center of the plate,

a base track ridge extending normal the plane of the plate and a uniform distance from the plate center and concentric with the shaft,

and a rst lip extending normal the plane of the rst plate from the periphery of the iirst plate and concentric With the track and shaft;

a second circular plate journalled over the shaft integral with the first plate,

and a second lip extending normal the plane of the second plate from the periphery of the second plate `and concentric with the shaft;

a spring mounted on the integral shaft and arranged to urge the plates together;

and a flexible element attached by one end to the second plate so as to be drawn from beneath the base track ridge through an .aperture in the ridge and out upon the base track ridge by the manual rotation of the second plate Where it is captured by the rst and second lips in forming the cam profile for actuating a follower to alternate positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,078,821 Walker Apr. 27, 1937 FOREIGN PATENTS 683,055 Germany Oct. 28, 1939 

